An electronic device may include a vent that allows air into or out of an electronic device. The vent can include a membrane formed from a porous material, thereby allowing air to permeate through the material. In some instances, the porous material also provides a barrier to water, and the electronic device may resist entry of the water.
However, in some instances, the air cannot escape the electronic device quickly enough through the porous material without disrupting another internal component of the electronic device. For example, an electronic device having a speaker module may include a diaphragm or membrane that is relatively thin and sensitive to pressure changes. When the diaphragm is exposed to internal air of the electronic device, changes in pressure of the internal air can cause unwanted vibrations to the diaphragm, causing the speaker module to generate noise. Also, depressing a touch screen, which causes the touch screen and a cover glass to bend, can reduce the internal volume of the electronic device, thereby increasing the air pressure. This may be particularly noticeable in water-resistant electronic devices that air substantially sealed to prevent water ingress. These water-resistant electronic devices may include a water-resistant membrane that impedes air movement (out of the electronic device) during an air pressure increase in the electronic device. Furthermore, when the touch screen is no longer depressed, both the touch screen and the cover glass return to their original (unbent) configuration, causing the internal volume to increase, thereby decreasing the air pressure. This process can also cause unwanted vibrations to the diaphragm. Accordingly, the water-resistant membrane may provide a relatively slow response time in removing air (in the case of decreased internal volume), and also in receiving air (in the case of increased internal volume).
In order to improve the response time, the size of the membrane may increase, thereby increasing the number of pores of the porous material, and/or increasing the size of each of the pores. However, the increased number of pores or increases size of the pores may decrease the water-resistant capabilities of the membrane, allowing water to enter the electronic device and potentially damage an internal component(s).